The invention relates to a light-transmitting optical device comprising a condenser element equipped with a first lens to concentrate the light in the opening of a second lens of an objective designed to emit or receive an optical beam.
Light-transmitting optical devices generally use a system of lenses and diaphragms arranged in an optical chamber. It is imperative to provide a mechanical support designed to position the different parts with respect to one another with precision. Opto-electronic barriers generally have two hundred monitoring light beams requiring a total of four hundred light-transmitting optical devices on the transmitter side and receiver side. The large number of mechanical supports increases the cost price of the installation.
A first object of the invention is to achieve a light-transmitting optical device in one single part able to eliminate any stray light rays not in the transmitting or receiving primary light beam passing through the objective. What is meant by primary light beam is all the light rays passing directly from one lens to the other. Any light ray taking a non-direct path is defined as being a stray ray.
The device according to the invention is characterized in that:
the first lens of the condenser element and the second lens of the objective are respectively arranged at one first end and at a second opposite end of an integrated optical module made of a transparent material having a predetermined refractive index,
the intermediate zone of said integrated optical module comprises a plurality of deflectors formed by a succession of dioptric surfaces arranged at intervals along the direction of propagation of the light flux between the first lens and the second lens so as to perform deflection outside the optical module of the stray rays reflected inside the optical module, thereby preventing transmission of said stray rays either through the second lens of the objective if a light transmission coming from the condenser element is involved, or through the first lens if receiving light coming from the second lens.
The single-piece structure of the optical light transmission device avoids the use of an optical chamber equipped with mechanical support and positioning parts. This results in a reduction of the overall cost of the optical light transmission device.
According to a preferred embodiment, a diaphragm can be associated to the first end of the integrated optical module and comprise a calibrated orifice to determine the angular opening of the useful optical beam emitted or received by the objective.
In the absence of a diaphragm, it is the size of the first lens that determines the angular opening of the optical beam emitted or received by the objective.
The second lens of the objective presents a preset focal distance whose focus is advantageously identical to the plane of the diaphragm.
In the absence of a diaphragm, the second lens constituting the objective presents a preset focal distance whose focus is identical to the opening plane of the first lens constituting the condenser.
The shape and positioning of the dioptric surfaces of the deflectors are chosen to ensure lateral ejection by refraction of the stray rays reflected in the integrated optical module.
According to one feature of the invention, the material of the integrated optical module has a quality of transparency in the 360 nm to 1560 nm pass-band.
According to another feature of the invention, the dioptric surfaces are alternately convergent and divergent being joined to one another by coaxial necks presenting increasing diameters in the direction of the objective so as to define with the diaphragm a primary optical cone inside the module.
A second object of the invention is to achieve a multichannel optical system using a plurality of integrated optical modules, preventing any light interference between the different channels.
An opto-electronic means is placed in each channel in front of the first lens of the corresponding condenser element and is formed either by a light-emitting diode in transmitter mode or by a photodiode in receiver mode. The different optical modules are integrated in parallel manner at regular intervals in a support plate equipped with salient fixing parts for clipping onto an electronic circuit housed inside a hollow elongate sectional part. The different modules of an optical system are joined to one another, opposite from the plate, by rigid connecting bridges whose front faces are cut into prisms and comprising in addition flexible tabs to act as pressure means when mechanical securing is performed inside the sectional part. The second lens of each objective of the optical modules is housed in an opening of the sectional part so as to be able to emit or receive the light beam.
Such a multichannel optical system can be used for constructing opto-electronic barriers equipped for protection of workers operating on dangerous machines.